The real issue comes down to my hauling my own water up there in the 80 gallon tank in the 27RLS (elite package).

Reliable water sources where we camp aren't guaranteed. If I tow without (or with less) water none of this is an issue.

But one of the main reasons we got the bigger water capacity is to be able to shower when we boondock.

Considering water weighs about 8 1/2 lbs. per gallon, that would be close to 700 lbs right there. Myself, I wouldn't want 700 lbs of water sloshing side-to-side while towing. It may not seem like it but, you'll definately notice it.

Considering water weighs about 8 1/2 lbs. per gallon, that would be close to 700 lbs right there. Myself, I wouldn't want 700 lbs of water sloshing side-to-side while towing. It may not seem like it but, you'll definately notice it.

You will have less sloshing front to back and side to side with full tanks than if they were 3/4 full or less

I have twice knowingly towed close my limits. Not over, but close. Two different trailers, and two different tow vehicles.

Both felt safe, both did the job. But they were adequate setups at best. Both were fine for short trips (under 200 miles) and on relatively flat terrain. But forget mountains, lots of hills, and high winds.

Towing with a tow vehicle that has a healthy capacity margin above the trailer's weights is a marked difference from towing close to limits. Far more comfortable and much easier on the tow vehicle.

The GVWR of the 27RLS is 8750 which is what it would weigh with all fluids, etc etc (80 gal water tank) right?

Not really, the GVWR is the MAX the TT should weigh after you put your "stuff" in it. Food, water, battery, chairs, clothes, propane...
That rating number is probably more related to the axles and or braking.
I always try to be below that number when travelling.

It's even possible that the combined weight rating of the tires could be less than your TT's GVWR but I think it's usually not.

If you really are cautious by nature a visit to the scales will give you a definitive answer.

My first trip to the scales was intimidating but I survived and was smarter than before (at least I felt smarter).
I've made a grand total of 3 scale trips and I always feel good about it.